Bracket.



0. H. SMITH.

BRACKET.

APPLICATION FILED APE.17, 1909.

0. H. SMITH.

BRACKET.

APPLICATION FILED APR. 11, 1909.

gLgesses .rnr: "mam: PETERS C0,, wasumcrou; n. c.

CHARLES H. SMITH, 0F CHICAGO, ILLINOIS.

BRACKET.

Specification of Letters Patent.

Patented Apr. 25, 1911.

Application filed April 17, 1909. Serial No. 490,457.

To all whom it may concern:

Be it known that I, CHARLES H. SMrrH, a citizen of the United States,residing in Chicago, county of Cook, and State of Illinois, haveinvented certain new and useful Improvements in Brackets, of which thefollowing is a specification.

This invention relates to extensible brackets, particularly those usedfor supporting dental appliances, telephones, drop lights, and the like,where it may be desirable to provide a bracket having a member at itsmovable end which retains a constant angular position for all of thevarious posit-ions into which the bracket may be moved. The invention isalso applicable to drafting or pantograph purposes where it is desirableto maintain the constant angular position of a ruler or straight edgeand to permit it to be moved to any position upon the surface of thedrafting board. The invent-ion is capable of many other uses such as thesupport of carving and drilling tools and such other devices as it isnecessary to support in a given direction and at the same time to moveas a whole into any position.

The invention comprises particularly the familiar lazy tongs arrangementin combination with new and improved means for maintaining theparallelism of the fixed and movable parts of the bracket, or in otherwords, maintaining the object upon the movable end of the bracket in afixed angular direction for all adjustments of the bracket.

The invention is more particularly set forth in the followingdescription and claims.

The invention is illustrated in the accompanying drawings, in whichFigure 1 is a side elevation of a support ing bracket in a partiallyextended position; Fig. 2 is a plan view of the same bracket; Fig. 3 isa plan view of a bracket as applied to drafting purposes, and Fig. 4: isa sectional detail showing the method of attaching the bracket to theedge of the drafting board.

In the drawing the members 6 of a lazy tongs construction are pivotedtogether in the usual manner to form a bracket which may be expanded orretracted and also inclined at various angles to the horizontal. At theattaching end these members 6 are pivotally supported between the cheeksof a sheet metal supporting member by means of the transverselyextending pivot 8. The supporting member is bent to form a sleeve 10which is fitted over a pin 11 on any suitable kind of fixture 12,forming a pivotal support about which the bracket may be swunghorizontally.

At the outer end of the lazy tongs is a clamp or holder 13 which may beof any de sired construction according to the device to be supported. Inthe illustrated embodiment this holder is of similar construction to thesupporting member and is provided with a sleeve which surrounds the rod14 porting the table 15. This sleeve is provided with the thumb screw 16for securely clamping the rod 14: if desired.

The constant angular position of the table in all positions of thebracket is maintained by means of a set of supplemental links 17 whichare pivoted at their ends and extend in parallelism to members 6 of thelazy tongs. At one end of the bracket the set of supplemental links ispivotally connected by means of a transverse pivot 18 between the cheeks7 of the supporting member, and at the other end of the bracket thesupplemental links are pivoted by means of transverse pivot 19 to theholding device 18. At each connecting point of the lower half of thelazy tongs the supplemental links are connected to the members of thelazy tongs by short links 20, the pivots employed to connect the membersof the lazy tongs together being also used to connect the short links asshown.

In order to permit the bracket to be extended and retracted to thegreatest extent possible and still maintain the supplemental links inthe same plane as the members of the lazy tongs the members of the lazytongs are concaved at the point 21 and the links 17 are made somewhatbowed in order that the pivotal points may when the device is eitherextended or collapsed approach as near as possible to the straight linebetween pivots.

As stated the supplemental links 17 are maintained in parallelism to themembers of for supthe lazy tongs in all positions of the bracket,

the distance between pivot centers of both being equal. Likewise theshort links 20 are maintained in parallelism with the line of centersbetween the pivots of the supporting member, the distance between thesecenters being also the same for the short links and the supporting andsupported members. Thus, through any and all positions of expansion,contraction or angular movement of the bracket as a whole, the supportedmember or holder 13 is maintained in a fixed and constant position.

For brackets such as are used in dental oflices it is desirable that themovable end may be changed from one position to another without a greatdeal of efl'ort and to accomplish this a counterbalancing means may beapplied, though for small brackets sufficient friction may be producedto hold the bracket in the desired position by means of the pivots whichmay have thumb screws applied thereto if desired.

In Fig. 1 is illustrated one method of counterbalancing the weight ofthe bracket and the objects supported thereby. In accordance with thismethod the rear links are extended beyond their supporting pivots andhave their ends connected by means of the links 22 which are pivotedtogether and support the adjustable weight 23 by means of the link 2 L.With this construction, the weight when adjusted to balance the bracketin one position will balance it in every position, the movement of theweight being such as to maintain its moment about the pivot 8 equal tothe moment of the bracket and the object carried thereby about the pivot8. It is to be understood, however, that other balancing means may beprovided such as springs, which are considered, when properly appliedfor this purpose, to be the mechanical equivalent of weights.

In Fig. 3 a similar bracket is shown applied to a drafting board, oneend being attached thereto by means of the hinged mem ber 25, and theother end carrying a protractor 26 to which the ruler or straight edge27 is attached in such manner as to permit its being moved to andsecured in any de sired angular position about the pivot 28. AV hen itis desired to use the drafting board with an ordinary T-square thebracket may be swung about the pivot or hinge 29 and allowed to hangdown at the side of the drafting table. The hinged member 25 is soarranged as to leave the end of the drafting board free for the use ofthe T-square when the bracket is not in use.

The same result, that of maintaining the movable end of the bracket in aconstant angular position for all positions of the bracket, may beaccomplished by means of several variations of the present invention,one of which is to use two separate sets of lazy tongs connected at thetwo ends and at an intermediate point by means of equal length links.This particular method is illustrated by dotted lines in the firstsection of the bracket of Fig. 3.

I, therefore, do not wish to be limited to the specific structures hereshown, various modifications being possible without departing from thespirit or scope of my invention.

I claim:

1. In an extensible bracket, the combination with a lazy tongs structurehaving attaching and supporting members at opposite ends, of a series oflinks pivotally connected together and extending parallel to the leversof the lazy tongs, the length between the pivots of the links beingequal to the dis tance between the pivots of the correspond ing leversof the lazy tongs, and asecond set of links connecting said pivots toeach other to maintain the parallelism of the first links and thelevers, substantially as described.

2. In an extensible bracket, the combination with lazy tongs havingattaching and supporting members at opposite ends, of a series of linkspivoted together, the links at the ends of the series being also pivotedto said members respectively, said links ex tending parallel to themembers of the lazy tongs, and the distance between the pivots of thelinks being equal to the distance between the pivots of the lazy tongs,and short links connecting the pivots of the lazy tongs with the pivotsof the links to maintain the parallelism of said parts, substantially asdescribed.

3. In an extensible bracket, the combination with lazy tongs, of asupplemental structure having members extensible and parallel with oneset of members of the lazy tongs, and links to maintain the parallelismof said members of the supplemental struc* ture with said members of thelazy tongs, substantially as described.

4:. In an extensible bracket, the combina tion with a lazy tongs, of aseries of supplemental links pivoted together and extensible andparallel with one set of members of the lazy tongs, and connectionsbetween the links and the lazy tongs constructed to maintain the formerin said parallelism, substantially as described.

5. In a bracket, the combination with the members of a lazy tongspivotally attached at one end to a support, of a table carried upon theother end of the bracket, and means extending along the lazy tongs topositively maintain said table level during the movement of the bracketup and down about said pivot, substantially as described.

6. In a bracket, the combination with a set of main links pivotedtogether so as to form an extensible structure known as lazy tongs, of aset of supplemental members connected by links to pivotal points of themain links and members at each end of the bracket'pivotally connected tothe main links and to the supplemental members and adapted to be movedto various distances from one another and to various angular positionsabout the pivots by which they are secured to the main links, thesupplemental links being adapted to maintain the endl members in aconstant angular relation with one another, substantially as described.

7. In a lazy tongs structure, a stationary member to which one end ofsaid lazy tongs is pivoted, a movable member pivoted to the other end ofthe lazy tongs, said pivots passing transversely to the plane of themembers of the lazy tongs, and supplemental means for maintaining theconstant angular direction of the latter member when the lazy tongs as awhole are swung about the pivot in the stationary member.

8. In a lazy tongs structure, the combina tion with a stationary member,a movable member, pivots extending transversely t0 the plane of themembers of the lazy tongs and securing the opposite ends of the lazytongs, respectively, to side members, articulated links extendingthroughout the length of the lazy tongs for holding the movable memberin a constant angular position during the movement of the lazy tongsstructure about the pivot in the stationary member.

Signed by me at Chicago, county of Cook, and State of Illinois, in thepresence of two witnesses.

CHARLES H. SMITH.

Vitnesses MAnJomE E. GRIER, M. LEAVER.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents,

Washington, I). G.

